Electromyography activity of the teres minor muscle with varying positions of horizontal abduction in the quadruped position

San Jose State University San Jose State University

SJSU ScholarWorks SJSU ScholarWorks

Faculty Research, Scholarly, and Creative Activity

5-29-2021

Electromyography activity of the teres minor muscle with varying Electromyography activity of the teres minor muscle with varying

positions of horizontal abduction in the quadruped position positions of horizontal abduction in the quadruped position

Masaaki Tsuruike

San Jose State University

, [email protected]

Todd S. Ellenbecker

Rehab Plus Physical Therapy Scottsdale and ATP Tour

Connor Lauffenburger

University of Northern Colorado

Follow this and additional works at: https://scholarworks.sjsu.edu/faculty_rsca

Part of the Biomechanics Commons, and the Motor Control Commons

Recommended Citation Recommended Citation

Masaaki Tsuruike, Todd S. Ellenbecker, and Connor Lauffenburger. "Electromyography activity of the teres

minor muscle with varying positions of horizontal abduction in the quadruped position"

JSES International

(2021): 480-485. https://doi.org/10.1016/j.jseint.2020.12.014

This Article is brought to you for free and open access by SJSU ScholarWorks. It has been accepted for inclusion in

Faculty Research, Scholarly, and Creative Activity by an authorized administrator of SJSU ScholarWorks. For more

information, please contact scholar[email protected].

Electromyography activity of the teres minor muscle with varying

positions of horizontal abduction in the quadruped position

Masaaki Tsuruike, PhD, ATC

, Todd S. Ellenbecker, DPT, MS, SCS, OCS, CSCS

Connor Lauffenburger, MA, LAT, ATC, CSCS

Department of Kinesiology, College of Health and Human Sciences, San Jos



e State University, San Jos



e, CA, USA

Rehab Plus Physical Therapy Scottsdale and ATP Tour, Scottsdale, AZ, USA

Sports Medicine Department, University of Northern Colorado, Greeley, CO, USA

article info

Keywords:

Horizontal abduction exercise

Quadruped position

Teres minor

Level of evidence: Basic Science Study;

Kinesiology

Background: The teres minor (TMi) muscle exposed relatively high activity during the acceleration and

deceleration phases of the throwing motion, compared with the infraspinatus muscle. However, few

studies have identiﬁed TMi muscle activity in intervention exercises. The purpose of this study was to

investigate TMi muscle activities in different horizontal adduction positions in the quadruped horizontal

abduction exercise. This study hypothesized that TMi muscle activity would differ in response to resis-

tance application across different horizontal adduction positions.

Materials and methods: Nineteen collegiate baseball players volunteered their participation. Raw

electromyography activity of the TMi muscle along with 7 different muscles attached to the scapula on

the dominant-side were collected, and normalized by each of the corresponding maximum voluntary

isometric contractions. All subjects performed manual isometric resistance horizontal abduction exer-

cises at 90



and 135



of abduction with 3 horizo ntal adduction angles in the quadruped position: 1)

coronal, 2) scapular, and 3) sagittal plane. Electromyography data were also collected from rhythmical

concentric contraction of horizontal abduction at 90



of abduction in the quadruped position.

Results: TMi muscle activity was signiﬁcantly greater with the arm positioned in the coronal plane than

that of the scapular and sagittal planes (41, 26, and 17% maximum voluntary isometric contraction,

respectively) (P < .05).

Conclusion: The present study demonstrated that TMi muscle activity varied depending on horizontal

adduction positions.

This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

The teres minor (TMi) muscle is the smallest of the rotator cuff

muscles and characterized as a thick fusiform without a pennate,

while the infraspinatus (IS) muscle is composed of a pennate.

External rotation (ER) force synergistically generated by the TMi

and IS muscles is cocontracted with the posterior deltoid (PD)

muscle.

The activation of the PD muscle increases in ER force as the

abduction (ABD) of the glenohumeral joint (GHJ) increases.

contrast, the tensile force of IS muscle, which was measured in a

cadaveric study, decreased as GHJ ABD increased owing to a

decrease in the rotational moment arm of the IS muscle, whereas

the TMi was not affected by GHJ ABD.

Although the TMi muscle

reportedly provides ER force up to 45%,

17,31

the TMi muscle may

play an important role in ER force in the 90



ABD position.

The amount of IS muscle activity has been demonstrated to be

signiﬁcantly decreased with elbow extension during standing

resistive band exercises with the arm positioned at 120



of ABD,

compared with the elbow ﬂexed at 90



with the arm positioned at



of ABD and ER of the GHJ.

This ﬁnding was in line with IS

muscle activity that was relatively less than TMi muscle activity

during the acceleration and deceleration phases of baseball pitch-

ing

12,14

in which the elbow joint was extended to 25



at ball release

from 110



of ﬂexion which occurred during the late cocking phase

of pitching motion along with the maximum external rotation of

the GHJ.

Furthermore, a previous study revealed that the mean

value of TMi muscle was most highly activated in prone shoulder

horizontal abduction (HABD) exercise and as much as side-lying ER

exercise among different exercises associated with a baseball

rehabilitation program.

However, few studies have investigated

TMi muscle electromyography (EMG) activity in intervention ex-

ercises compared with the IS muscle across the different horizontal

adduction (HADD) positions. Therefore, the purpose of this study

was to investigate TMi muscle activity in different arm positions of

This study was approved by the Ofﬁce of Research, San Jos



e State University (IRB

Protocol F18117).

* Corresponding author: Masaaki Tsuruike, PhD, ATC, One Washington Square,

San Jos



e, CA 95192-0054, USA.

E-mail address: [email protected] (M. Tsuruike).

Contents lists available at ScienceDirect

JSES International

journal homepage: www.jsesinternational.org

https://doi.org/10.1016/j.jseint.2020.12.014

(http://creativecommons.org/licenses/by/4.0/).

JSES International 5 (2021) 480e485

HADD to determine which arm position produced the highest

levels of TMi muscle activity using manual resistance with subjects

in a quadruped position. This study hypothesized that TMi muscle

activity would vary with the amount of HADD position during

quadruped exercise. Because this study used a surface EMG elec-

trode to measure TMi muscle activity, adjacent muscle activities

were measured to distinguish any potential contamination of

crosstalk signals.

Methods

During the baseball off-season, 19 male collegiate baseball

players belonging to the NCAA D-I conference (height: 181.4 ± 8.1

cm, weight: 86.7 ± 10.0 kg, age: 18.9 ± 1.1 years) volunteered to be

examined. All participants gave informed consent to the proced-

ures as approved by the institutional review board of the university

before testing. All subjects were asymptomatic, competitive base-

ball players without neurologic or physiological injuries in the

upper body based on the completion of a preliminary screening

questionnaire. All tests were performed in the Kinesiology

Laboratory.

Electrode Placement

Raw EMG amplitudes of the TMi, IS, teres major (TMa), PD,

middle deltoid (MD), upper trapezius (UT), lower trapezius (LT),

and serratus anterior (SA) muscles on the throwing shoulder side

were collected. Bipolar surface silver (Ag) EMG electrodes with a

bar length of 10 mm, width of 1 mm, and a distance of 10 mm

between active recording sites (Delsys Bagnoli-8, Delsys Inc.,

Natick, MA, USA) were used. The EMG electrodes were preampliﬁed

(X 10) and routed through the EMG mainframe, which further

ampliﬁed (X 100) and band-pass ﬁltered (20-450 Hz) the signals.

Electrodes were placed on the center of the muscle belly in line

with the muscle ﬁbers for the speci ﬁc manual muscle test.

The electrode for the TMi muscle was placed on one-third of the

distance from the posterior portion of the acromion process to the

inferior angle of the scapula and the lateral aspect of the lateral

border of scapula, which was just below the deﬁnition of the PD

muscle

(Fig. 1). Because surface EMG recordings were used in this

study, we presumed that for the theoretical basis of the study, this

electrode location was representative of TMi function in our

subjects. For the IS muscle, the electrode was placed on inferior and

parallel to the scapular spine over the infrascapular fossa,

3,29

while

the electrode was placed on the lateral aspect of the inferior angle

of scapula for the TMa muscle. For the PD muscle, the electrode was

placed at an oblique direction parallel to the muscle ﬁbers of the

deltoid muscles at the lateral border of the scapular spine;

while

the electrode was place at halfway between the tip of acromion and

the deltoid tubercle for the MD muscle.

3,29

For the UT muscle, the

electrode was placed at halfway between the C7 spinous process

and the acromion process, while the electrode was placed at an

oblique angle from the scapular spine and just outside of the

scapular medial border for the LT muscle.

For the SA muscle, the

electrode was placed below the axilla between the latissimus dorsi

and pectoralis major at the level of the scapular inferior

angle.

26,27 ,29,30

The reference electrode was placed over the spine of

the scapula or between the electrodes of the UT and IS muscle.

Procedures

Once the electrodes were secured, participants performed a 4-

second maximum voluntary isometric contraction (MVIC) after

ramp-up contraction for each muscle using the manual muscle

strength test (MMT) procedure for normalization of EMG data. The

manual pressure was applied by the same examiner for all testing

positions to determine each of the MVICs. For the MVICs of the UT

and SA, subjects abducted their arms to 90



in the scapular plane

with the elbows extended and the thumb pointed toward the

ceiling and resisted downward pressure applied on the arm,

whereas for the MD, the MVIC was examined in 90



of ABD of

the GHJ with the elbow ﬂexed.

The MVIC of the IS was examined

while the subjects resisted the manual pressure applied toward

internal rotation of the shoulder with the elbow ﬂexed to 90



shoulder abducted to 0



and externally rotated to 0



The MVICs

of the LT and PD were examined in the quadruped position while

the subjects elevated their arm to 135



ABD and resisted downward

pressure applied on the arm.

The MVICs of the TMi and TMa were

examined in the quadruped position at 90



ABD and at 0



of hori-

zontal ABD with the elbow ﬂexed to 90



while the subjects resisted

downward pressure applied on the arm.

The amount of force (N) of MMT was determined in both 90 and

135



ABD without ER in quadruped horizontal abduction per-

formed in the coronal plane by the same examiner with a handheld

dynamometer (MicroFET, Hoggan Scientiﬁc, LLC, Salt Lake City, UT,

USA) for each subject. The MMT force was subsequently used to

determine the percentage of external load in horizontal adduction.

All subjects performed manual isometric resistance exercises

against external loads in 3 HADD angles in a quadruped position for

EMG data collection: 1) 0



of HADD or the arm positioned in the

sagittal plane, 2) 50



of HADD or the arm positioned in the scapular

plane, and 3) 90



of HADD or the arm positioned in the coronal

plane. The subjects were required to lift the exercise arm off the

table during the quadruped position (Fig. 2). Isometric resistance

exercises were implemented at 2 different shoulder abduction

angles: 90



and 135



of ABD for 10 seconds each. The external load

of 40% MMT were given just above the posterior portion of the

elbow that was ﬂexed in each of the 3 arm positions during the

quadruped HABD resistance exercise, which was determined

before the exercises for each subject. The amount of exercise in-

tensity was selected as described by Bitter et al

3,6

who demon-

strated that the amount of infraspinatus EMG activity was

signiﬁcantly greater at 40% MMT with less contribution of MD and

PD muscle activity than at 10% or 70% MMT in external rotation. The

subjects were asked to match the manual resistance pressure given

for each of the 3 HADD angles. Each subject performed all the

manual isometric resistance exercises at 0



(or in the sagittal

Figure 1 Deﬁnition of the teres minor (TMi), infraspinatus (IS), posterior deltoid (PD),

teres major (TMa), and latissimus dorsi during horizontal abduction exercise with the

elbow extended and shoulder externally rotated while pulling a cable machine.The

photo depicts a female subject who did not participate in this study. Typically, the

muscular deﬁnition of the TMi muscle is unclear in many male subjects who are

trained owing to the hypertrophy of the deltoid muscles.

M. Tsuruike, T.S. Ellenbecker and C. Lauffenburger JSES International 5 (2021) 480e485

481

plane), 50



(or in the scapular plane), and 90



(or in the coronal

plane) of HADD in each of the arm positions of ABD (90



and 135



)

in a randomized order to minimize the systematic effect of motor

learning and fatigue.

To clarify the exercise intensity of 40% MMT in the quadruped

HABD isometric manual resistance exercise, this study included

quadruped isotonic contractions with the same tested arm moving

backward and forward about for 90



of HADD ranging from the

sagittal to coronal plane and vice versa with the elbow joint ﬂexed

to 90



. The exercise was implemented with 2 different wrist cuff

weights: 1.4 kg (3 lb) and 3.2 kg (7 lb), which was commonly used

in shoulder rehabilitation exercises.

Based on our pilot study, the

cadence of the exercises was controlled by a metronome set at 75

beats per minute. The subjects performed rhythmical isotonic ex-

ercises with the weight load of 1.4 kg followed by the weight load of

3.2 kg for 10 times each. It was believed that this exercise protocol

would help understand TMi EMG activity compared with IS and PD

EMG activities.

Data analysis

The EMG activities were collected using a data collection pro-

gram (MP 150 Data Acquisition System; Biopac System, Inc., Goleta,

CA, USA) with a sample rate of 1000 Hertz. All data were recorded

and stored in a computer for off-line analysis. The mean EMG ac-

tivity of the middle 2 seconds of each 4-second isometric

contraction was calculated to determine the individual’s MVIC. For

the isometric exercise condition, the mean EMG activity of the

middle 5 seconds was calculated. All data were calculated in root

mean square (RMS) values, normalized to MVIC of the corre-

sponding muscles, and presented as a percentage of MVIC (% MVIC).

A 2 x 3 (ABD x HADD) repeated measures analysis of variance

design within subjects crossed with arm positions was used to

determine if there was any signiﬁcant difference in mean values of

normalized EMG muscle activity. A 1-way analysis of variance

design was also used to determine any difference in the mean

values of normalized EMG muscle activity across the rhythmical

isotonic contractions with 2 different weight loads and isometric

contraction at the coronal plane. Where appropriate, the simple

main effect and a post hoc test with Tukey honestly signi ﬁcant

difference were used to determine any signiﬁcant difference. The

level of signiﬁcance was set at the 0.05 level.

Results

The mean force values produced in the quadruped HABD at 90



and 135



ABD arm positions were determined as follows: 167.0 N

and 157.8 N, respectively. Analysis of the results indicated no dif-

ference in the amount of the force the 90



and 135



ABD arm

positions.

No signiﬁcant interactions were observed for TMi, IS, TMa, and

UT activities. However, signiﬁcant main effects of HADD positions

were observed for the marginal mean values of the 4 muscle ac-

tivities (Table I). In addition, signiﬁcant main effects of the ABD arm

positions were observed for TMa activities (22.8 ± 15.4 and

16.9 ± 15.0% MVIC, 90



and 135



ABD, respectively) and for UT

activities (15.0 ± 12.3 and 22.2 ± 12.1% MVIC, 90



and 135



ABD,

respectively), while no signiﬁcant main effects were observed

between the 2 ABD arm positions for both TMi and IS activities.

Analysis of the results indicated a signiﬁcant interaction

between ABD and HADD angles for PD, MD, and LT activities

(Table II). For SA muscle activity, no signiﬁcant interaction or main

factor of HADD positions was observed, while a signiﬁcant differ-

ence was observed between 90



and 135



ABD (7.3 ± 5.1 and

10.9 ± 9.2% MVIC, 90



and 135



ABD, respectively).

The intensity of HADD manual resistance exercise with 40%

MMT was identiﬁed as greater than that of rhythmical isotonic

contraction exercise with the wrist cuff weight of 3.2 kg from the

perspective of PD and MD muscle activities. As a result, the

amounts of both TMi and IS muscle activities in the isotonic exer-

cise were signiﬁcantly less than those of manual resistance exercise

(P < .05). Table III shows each of the mean values for muscle

activities across isotonic exercises with the weight load of 1.4 kg

and 3.2 kg and isometric contraction with the load of 40% MMT.

Discussion

The ﬁndings of results were in line with the previous study in

which TMi muscle activity was signiﬁcantly increased during the

standing 90/90 ER resistive band exercise when another resistive

Figure 2 Manual isometric resistance exercise was implemented in the quadruped position. The 3 different arm position angles were shown during the exercise at 0 of abduction of

the glenohumeral joint: (left) 90 of horizontal adduction (HADD) or the arm positioned in the sagittal plane, (middle) 50 of HADD or the arm positioned in the sagittal plane, and

(right) 90 of HADD or the arm positioned in the frontal plane.

M. Tsuruike, T.S. Ellenbecker and C. Lauffenburger JSES International 5 (2021) 480e485

482

band was added to the distal portion of arm which augmented

horizontal abduction resistance in the coronal plane, whereas it

was not increased in the scapular plane.

IS muscle activity is

decreased in ER force as the arm is abducted whereas TMi muscle

activity is not.

20,24

Using positron emission tomography, Kurokawa

et al

identiﬁed that the TMi muscle generated higher muscle

activity in ABD of the GHJ after ER exercise for 5 minutes in the

supine position, while the IS muscle generated higher muscle ac-

tivity in adduction of the GHJ. Moreover, Hamada et al

compared

the amount of TMi muscle activity between ﬂexion and ABD of the

GHJ without ER, and found that the maximum level of TMi muscle

activity was progressively increased when the arm was ﬂexed up to

120



or abducted up to 150



. They also conﬁrmed greater activity of

the TMi muscle in ER at 90



of GHJ ABD than in ER at 0



of ABD.

The ﬁndings of this study suggest that the IS muscle is not

involved with HABD force as much as the TMi muscle at 90



of ABD.

This might be attributed to different anatomical positions between

the 2 muscles although the 2 muscles function as synergistic

muscles of GHJ ER torque. The TMi muscle is innervated by the

posterior axillary nerve, whose branch innervates the PD muscle,

whereas the IS muscle is innervated by the suprascapular

nerve.

2,4,19

The TMi muscle inserts into the posteroinferior portion

of the greater tuberosity aligned with the surgical neck of the hu-

merus and from 3 to 5 o’clock, compared to the IS muscle, which

inserts from 1 to 3 o’clock and is wrapped around the posterior

aspect of the supraspinatus muscle insertion area.

9,15

Thus, it is

plausible to propose that the TMi muscle can be involved with the

PD muscle to produce horizontal ABD, whereas the IS muscle is less

likely involved with horizontal ABD at 90



of ABD.

During surgical repair of the rotator cuff, only 1% of cases

involved a repair of the TMi tendon, compared with the supra-

spinatus tendon which was involved in up to 75% of the total

number of 581 rotator cuff surgeries in professional baseball

players.

Thirty-eight percent of the throwing athletes were only

able to return to the same level of play or higher after rotator cuff

repairs although 79% of the athletes were able to return to play.

The occupational ratio of the TMi muscle can be increased as

compensational hypertrophy in shoulders with tears in the supra-

spinatus and IS muscles.

In addition, relatively high activity of the

TMi muscle was observed during acceleration, deceleration, and

follow-through phases of throwing, compared with the activity of

IS muscle.

Indeed, more than a half of female professional tennis

players were able to play tennis with IS muscle atrophy whose

mechanism was unknown on their dominant side.

Furthermore,

4% of professional pitchers were identiﬁed to have IS muscle atro-

phy.

Therefore, in addition to ER exercise in the shoulder adduc-

tion position commonly recommended for individuals with rotator

cuff injuries,

23,32

we recommend that individuals with symptom-

atic shoulders owing to habitual overhead performance include

resistive exercise in 90



horizontal ABD at the coronal plane level.

Table I

The marginal mean values and standard deviations (in parentheses) of normalized EMG activity (% MVIC) of the teres minor, infraspinatus, teres major, and upper trapezius

across in the 3 different arm position.

Muscle activity Horizontal adduction F ratio P value Critical



Teres minor 15.5 (8.0) 26.2 (10.7) 41.4 (14.2) 146.4 <.001 3.71

Infraspinatus 8.6 (4.4) 13.0 (6.2) 19.2 (8.7) 68.1 <.001 2.62

Teres major 11.5 (7.9) 19.6 (13.0) 29.0 (18.2) 32.4 <.001 6.83

Upper trapezius 10.1 (9.1) 16.8 (9.1) 28.9 (11.8) 67.1 <.001 5.05

% MVIC, percentage of maximum voluntary isometric contraction; EMG, electromyography.

F ratios (2, 36) for each of the main factors and Tukey HSD critical values were shown for each of the differences in the mean values (P < .05).

Table II

The mean values and standard deviations (in parentheses) of normalized EMG activity (% MVIC) of the posterior deltoid, middle deltoid, and lower trapezius between 90



and

135



of abduction across at 0



of horizontal adduction (HADD) or the arm positioned in the sagittal plane, 50



of HADD or the arm positioned in the scapular plane, and 90



HADD or the arm positioned in the coronal plane in the quadruped position.

Muscle activity 90



abduction 135



abduction F ratio Critical



Posterior deltoid 19.0 (5.0)yy 30.1 (6.6)*yy 53.4 (12.5)yy 24.3 (12.1)yy 42.0 (17.2)*yy 55.4 (17.0)yy 5.50 5.95

Middle deltoid 13.4 (3.9)*yy 25.4 (7.3)*yy 49.5 (14.5)yy 22.7 (10.4)yy 37.5 (14.3)*yy 52.6 (14.8)*yy 5.21 6.11

Lower trapezius 23.0 (7.7)*y 28.9 (8.6)y 34.4 (14.3)*yy 14.1 (8.7)*yy 28.5 (10.7)yy 44.2 (15.8)*yy 17.1 6.47

% MVIC, percentage of maximum voluntary isometric contraction; EMG, electromyography.

F ratios (2, 36) for each of the interventions for each of the muscle activities and Tukey HSD critical values were shown for each of the differences in the mean values for each of

the muscles (P < .05). The asterisk (*) indicates a signiﬁcant simple main effect between 90



and 135



of ABD for each of the HADD angles (P < .05). The dagger (y) indicates a

signiﬁcant difference across the HADD angles for each of the arm position at 90



and 135



of ABD for each of the muscle activities with the critical value (P < .05).

Table III

The mean values and standard deviations (in parentheses) of normalized EMG ac-

tivity (% MVIC) of the eight muscle activities measured in the quadruped rhythmical

concentric contraction with the wrist cuff weights of 1.4 and 3.2 kg and horizontal

abduction manual resistance in the coronal plane with 40% manual muscle strength

test (MMT).

Muscle activity Isotonic contraction 40% MMT F ratio Critical

1.4 kg 3.2 kg Coronal plane

Teres minor 25.1 (8.6)* 32.8 (13.3)* 41.2 (11.7)** 12.7 8.3

Infraspinatus 12.4 (4.2)* 14.1 (4.3)* 18.5 (8.4)** 12.8 3.2

Teres major 22.2 (12.7)* 27.3 (12.8) 33.0 (16.0)* 9.14 6.7

Posterior deltoid 31.5 (9.3)* 37.4 (14.0)* 53.4 (12.5)** 25.4 8.3

Middle deltoid 27.5 (7.6)* 33.2 (10.8)* 49.5 (14.5)** 20.3 9.2

Upper trapezius 27.2 (9.3) 33.0 (11.1) 26.3 (12.8) 3.28

Lower trapezius 40.3 (13.1) 44.7 (13.4)* 34.4 (14.3)* 3.59 8.6

Seeratus anterior 8.8 (9.4) 8.6 (7.9) 6.3 (5.1) 0.35

% MVIC, percentage of maximum voluntary isometric contraction; EMG , electro-

myography; HSD, honestly signiﬁcant difference.

F ratios were shown for each of the main factors and Tukey HSD critical values were

shown for each of the differences in the mean values (P < .05). The asterisk (*) in-

dicates a signiﬁcant difference in % MVIC across the quadruped rhythmical con-

tractions with different weights and isometric contraction with 40% MMT in the

coronal plane.

M. Tsuruike, T.S. Ellenbecker and C. Lauffenburger JSES International 5 (2021) 480e485

483

Rhythmical isotonic contraction moving backward and forward

between the sagittal and coronal plane with the wrist cuff weight of

3.2 kg did not activate the TMi muscle as much as manual isometric

resistance at the coronal plane with the external load of 40% MMT.

However, it signiﬁcantly decreased MD muscle activity up to the

moderate level,

which might minimize the superior translation of

humeral head.

3,6

From the perspective of clinical implication, it

would be beneﬁcial for individuals with subacromial pain syn-

drome to perform quadruped isotonic movement or isometric

resistance up to the scapular plane, which signiﬁcantly decreased

MD muscle activity as well.

With regard to limitations, this study included a sample

delimited to 1 cohort of collegiate baseball players, all of whom

were highly trained to prepare for their upcoming season and had

asymptomatic shoulders at the time of data collection. The subjects

of this study may have developed TMi muscle strength as a result of

their sports speciﬁcity and adaptation. Thus, the ﬁndings may limit

the generalization regarding age and the level of performance to

other populations and conditions.

This study used an active surface EMG electrode with a distance

of interelectrode spacing of surface EMG of 10 mm which can

reduce the contamination of crosstalk signals as compared with

that of 22 mm.

In addition, De Luca et al

pointed out that the

amount of EMG amplitude was much less in the musculotendon

junction detected by the surface electrode than by the signal

detected in the midline of the muscle belly. Thus, potential cross-

talk between the TMi muscle and the long head of triceps brachii,

located underneath the TMi muscle, appears trivial. In this study,

both the TMi and TMa muscle were differently activated based on

the results of this study, whereas we cannot completely remove the

crosstalk signal from the PD muscle for the quality of TMi muscle

activity measured using the surface EMG electrode.

Conclusion

This study presented the careful selection of arm position that

generates TMi muscle activity during the quadruped horizontal

abduction exercise in the coronal plane more than that of the

scapular and sagittal planes. Further studies are warranted to

investigate TMi muscle activity to guide injury prevention and

rehabilitation especially for overhead athletes.

Disclaimers:

Funding: No funding was disclosed by the authors.

Conﬂicts of interest: The authors, their immediate families, and any

research foundations with which they are afﬁliated have not

received any ﬁnancial payments or other beneﬁts from any com-

mercial entity related to the subject of this article.

Acknowledgments

The authors thank Deanna Geraci, MA, ATC, for her assistance

with data collection during this study.

References

1. Altintas B, Anderson N, Dornan GJ, Boykin RE, Logan C, Millett PJ. Return to

sport after arthroscopic rotator cuff repair. Am J Sports Med 2020;48:252-61.

https://doi.org/10.1177/0363546519825624.

2. Bacle G, Gregoire JM, Patat F, Clavert P, De Pinieux G, Laulan J, et al. Anatomy

and relations of the infraspinatus and the teres minor muscles: a fresh cadaver

dissection study. Surg Radiol Anat 2017;39:119-26. https://doi.org/10.1007/

s00276-016-1707-9.

3. Bitter NL, Clisby EF, Jones MA, Magarey ME, Jaberzadeh S, Sandow MJ. Relative

contributions of infraspinatus and deltoid during external rotation in healthy

shoulders. J Shoulder Elbow Surg 2007;16:563-8. https://doi.org/10.1016/

j.jse.2006.11.007.

4. Chaﬁk D, Galatz LM, Keener JD, Kim HM, Yamaguchi K. Teres minor muscle and

related anatomy. J Shoulder Elbow Surg 2013;22:108-14. https://doi.org/

10.1016/j.jse.2011.12.005.

5. Chalmers PN, Erickson BJ, D'Angelo J, Ma K, Romeo AA. Epidemiology of

shoulder surgery among professional baseball players. Am J Sports Med

2019;47:1068-73. https://doi.org/10.1177/0363546519832525.

6. Clisby EF, Bitter NL, Sandow MJ, Jones MA, Magarey ME, Jaberzadeh S. Relative

contributions of the infraspinatus and deltoid during external rotation in pa-

tients with symptomatic subacromial impingement. J Shoulder Elbow Surg

2008;17(1 Suppl):87S-92S. https://doi.org/10.1016/j.jse.2007.05.019.

7. Cools AM, Dewitte V, Lanszweert F, Notebaert D, Roets A, Soetens B, et al.

Rehabilitation of scapular muscle balance: which exercises to prescribe? Am J

Sports Med 2007;35:1744-51. https://doi.org/10.1177/0363546507303

560.

8. Cummins CA, Messer TM, Schafer MF. Infraspinatus muscle atrophy in pro-

fessional baseball players. Am J Sports Med 2004;32:116-20. https://doi.org/

10.1177/0363546503260731.

9. Curtis AS, Burbank KM, Tierney JJ, Scheller AD, Curran AR. The insertional

footprint of the rotator cuff: an anatomic study. Arthroscopy 2006;22:603-9.

https://doi.org/10.1016/j.arthro.2006.04.001.

10. De Luca CJ, Kuznetsov M, Gilmore LD, Roy SH. Inter-electrode spacing of surface

EMG sensors: reduction of crosstalk contamination during voluntary contrac-

tions. J Biomech 2012;45:555-61. https://doi.org/10.1016/

j.jbiomech.2011.11.010.

11. De Luca CJ. The use of surface electromyography in biomechanics. J Appl Bio-

mech 1997;13:135-63.

12. Digiovine NM, Jobe FW, Pink M, Perry J. An electromyographic analysis of the

upper extremity in pitching. J Shoulder Elbow Surg 1992;1:15-25.

13. Escamilla RF, Slowik JS, Diffendaffer AZ, Fleisig GS. Differences among over-

hand, 3-quarter, and sidearm pitching biomechanics in professional baseball

players. J Appl Biomech 2018;34:377-85. https://doi.org/10.1123/jab.2017-

0211.

14. Gowan ID, Jobe FW, Tibone JE, Perry J, Moynes DR. A comparative electro-

myographic analysis of the shoulder during pitching. Professional versus

amateur pitchers. Am J Sports Med 1987;15:586-90.

15. Hamada J, Nimura A, Yoshizaki K, Akita K. Anatomic study and electromyo-

graphic analysis of the teres minor muscle. J Shoulder Elbow Surg 2017;26:

870-7. https://doi.org/10.1016/j.jse.2016.09.046.

16. Kibler WB, Sciascia AD, Uhl TL, Tambay N, Cunningham T. Electromyographic

analysis of speciﬁc exercises for scapular control in early phases of shoulder

rehabilitation. Am J Sports Med 2008;36:1789-98. https://doi.org/10.1177/

0363546508316281.

17. Kikukawa K, Ide J, Kikuchi K, Morita M, Mizuta H, Ogata H. Hypertrophic

changes of the teres minor muscle in rotator cuff tears: quantitative evaluation

by magnetic resonance imaging. J Shoulder Elbow Surg 2014;23:1800-5.

https://doi.org/10.1016/j.jse.2014.03.014.

18. Kurokawa D, Sano H, Nagamoto H, Omi R, Shinozaki N, Watanuki S, et al.

Muscle activity pattern of the shoulder external rotators differs in adduction

and abduction: an analysis using positron emission tomography. J Shoulder

Elbow Surg 2014;23:658-64. https://doi.org/10.1016/j.jse.2013.12.

021.

19. Melis B, DeFranco MJ, L

€

adermann A, Barthelemy R, Walch G. The teres minor

muscle in rotator cuff tendon tears. Skeletal Radiol 2011;40:1335-44. https://

doi.org/10.1007/s00256-011-1178-3.

20. Otis JC, Jiang CC, Wickiewicz TL, Peterson MG, Warren RF, Santner TJ. Changes

in the moment arms of the rotator cuff and deltoid muscles with abduction and

rotation. J Bone Joint Surg Am 1994;76:667-76.

21. Rathi S, Zacharias A, Green RA. Veriﬁcation of a standardized method for

inserting intramuscular electromyography electrodes into teres minor using

ultrasound. Clin Anat 2015;28:780-5. https://doi.org/10.1002/ca.22561.

22. Reinold MM, Wilk KE, Fleisig GS, Zheng N, Barrentine SW, Chmielewski T, et al.

Electromyographic analysis of the rotator cuff and deltoid musculature during

common shoulder external rotation exercises. J Orthop Sports Phys Ther

2004;34:385-94. https://doi.org/10.2519/jospt.2004.34.7.385.

23. Robinson HA, Lam PH, Walton JR, Murrell GAC. The effect of rotator cuff repair

on early overhead shoulder function: a study in 1600 consecutive rotator cuff

repairs. J Shoulder Elbow Surg 2017;26:20-9. https://doi.org/10.1016/

j.jse.2016.05.022.

24. Ryan G, Johnston H, Moreside J. Infraspinatus Isolation During External Rota-

tion Exercise at Varying Degrees of Abduction. J Sport Rehabil 2018;27:334-9.

https://doi.org/10.1123/jsr.2016-0217.

25. Townsend H, Jobe FW, Pink M, Perry J. Electromyographic analysis of the

glenohumeral muscles during a baseball rehabilitation program. Am J Sports

Med 1991;19:264-72.

26. Tsuruike M, Ellenbecker TS, Kagaya Y Lemings L. Analysis of scapular muscle

EMG activity during elastic resistance oscillation exercises from the perspec-

tive of different arm positions. Sports Health 2020;12:395-400. https://doi.org/

10.1177/1941738120929305.

27. Tsuruike M, Ellenbecker TS, Lauffenburger C. The application of

doub le elastic band exercise in the 90/90 arm position for overhead ath-

letes. Sports Health 2020;12:495- 500. ht tps://doi.org/10.1177/19417381

20935441.

M. Tsuruike, T.S. Ellenbecker and C. Lauffenburger JSES International 5 (2021) 480e485

484

28. Tsuruike M, Ellenbecker TS. Adaptation of muscle activity in scapular dyski-

nesis test for collegiate baseball players. J Shoulder Elbow Surg 2016;25:1583-

91. https://doi.org/10.1016/j.jse.2016.03.004.

29. Tsuruike M, Ellenbecker TS. Scapular muscle electromyographic activity during

abduction exercises in the scapular plane in three positions. Int J Sports Phys

Ther 2019;14:935-44.

30. Tsuruike M, Ellenbecker TS. Serratus anterior and lower trapezius muscle ac-

tivities during multi-joint isotonic scapular exercises and isometric contractions.

J Athl Train 2015;50:199-210. https://doi.org/10.4085/1062-6050-49.3.80.

31. Walch G, Boulahia A, Calderone S, Robinson AH. The 'dropping' and 'horn-

blower's' signs in evaluation of rotator-cuff tears. J Bone Joint Surg Br 1998;80:

624-8.

32. Weiss LJ, Wang D, Hendel M, Buzzerio P, Rodeo SA. Management of rotator cuff

injuries in the elite athlete. Curr Rev Musculoskelet Med 2018;11:102-12.

https://doi.org/10.1007/s12178-018-9464-5.

33. Young SW, Dakic J, Stroia K, Nguyen ML, Harris AH, Safran MR. High incidence

of infraspinatus muscle atrophy in elite professional female tennis players. Am

J Sports Med 2015;43:1989-93. https://doi.org/10.1177/0363546515588177.

M. Tsuruike, T.S. Ellenbecker and C. Lauffenburger JSES International 5 (2021) 480e485

485